Video technology relates to electronically capturing, processing, recording, and reconstructing a sequence of still images referred to as frames, so as to represent motion. Video includes a number of frames based on a predefined frame rate. For example, in the U.S., the Advanced Television Systems Committee (“ATSC”) establishes a standard frame rate of 29.97 frames/second for video used for commercial broadcasting.
For video transmitted via a digital video signal (e.g., based on the high definition serial digital interface (HD-SDI) standard), each frame is represented by a number of pixels commonly described as the smallest unit of an image that can be represented or controlled. The number of pixels in a frame is based on a predefined resolution of the frame (typically defined by a number of columns and rows of pixels). For example, a frame having a resolution of 1920 columns and 1080 rows is referred to as 1920×1080 and is represented by the arithmetic product of approximately 2,073,600 pixels. Pixels have many attributes, including for example, chrominance values that represent color, and luma values (referred to herein as lumas) that represent brightness. Once captured and processed, video is typically encoded and recorded as a digital file. Thereafter, the file is retrieved and the video is reconstructed by decoding the file.
For a variety of reasons, such as to assist with video editing, it is generally considered useful and helpful to analyze video frames and identify select types of frames. One such type is a colorbar frame, which is one that displays a static arrangement of colored bars. These bars are commonly referred to as Society of Motion Picture and Television Engineers (“SMPTE”) colorbars and are used as a type of television test pattern.
An example of a colorbar frame is shown in FIG. 1, and generally designated 100. The colorbar frame 100 includes three rows of bars. A first row 102 has seven relatively tall bars, each having a chrominance value representing a color. In order from left to right, the bars are generally light gray, yellow, cyan, green, magenta, red, and blue. These bars represent all seven possible color combinations that use at least one of the three chrominance value components of red, green, and blue, with blue cycling on and off between every bar, red cycling on and off between every two bars, and green cycling on for the leftmost four bars and off for the rightmost three bars.
In the colorbar frame 100, a second row has seven relatively short bars, again each having a chrominance value representing a color. In order from left to right, the bars are generally blue, black, magenta, black, cyan, black, and light gray. Finally, a third row 106 has eight relatively medium height bars (having various widths), again with each having a chrominance value representing a color. In order from left to right, the bars are generally dark blue, white, purple, black, black, dark gray, gray, and black.
While one example of a colorbar frame has been discussed, there are several variations of colorbar frames. For example, some colorbar frames may include only a first row, wherein the tall bars extend the entire height of the frame. Other colorbar frames may include variations in the positions and counts of rows or bars, and/or may include variations in the specific colors of the bars, and certainly other variations and examples are possible. The vast majority of colorbar frames, however, contain certain common characteristics; for example, each bar is a generally uniform color.